This character, which I'm referring to as "Mysterious Enemy" as to not give away what he's reveled to be, is a strange being that follows the play and often gives cryptic messages.  His voice is very deep and menacing with a slight English accent and a somewhat slow delivery.  Think of almost a James Earl Jones-type.  A near perfect example of what I'm looking for is the Beast from the miniseries Over the Garden Wall.  You can watch a scene of the Beast HERE.  Minor ad-libs are welcomed, but don't stray too far from the lines that are given.